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Only Rain Down the Drain

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Save and keep local waters clean!
See our Guide to Car Washing in San Francisco.

Most of San Francisco has a combined sewer system that combines and treats both wastewater and stormwater prior to discharging into the Pacific Ocean or San Francisco Bay. However, parts of the city are served by separate storm sewer systems, where wastewater is transported and treated in one system and stormwater is transported through a separate system directly into receiving waters without treatment. These separate storm sewers are located on the outer edges of the city and can be found in Ocean Beach, Lake Merced, and Mission Bay. In these parts of the city, it is especially important to that only rain enters these storm drains.

Keep Pollutants Out of the System

Pollutants such as trash, pet waste, pesticides, and motor oil may end up in our storm drain. Here are several ways you can prevent pollution in our storm drains:

  1. Use less-toxic gardening products in your garden.
  2. Properly dispose of pesticides that remove lice, ticks, fleas, ants, and any other outdoor pest.
  3. Dispose of household chemicals at a recycling center or household hazardous waste facility.
  4. Always pick up your pet’s waste and throw the bagged waste in the trash.
  5. Never litter, dispose of trash properly.
  6. Remove some of the concrete in your front “yard” and plant a tree or make a rain garden.
  7. Ride a bike or take public transportation instead of driving alone to work can reduce the amount of harmful car exhaust pollutants from the street.
  8. Attend a Coastal Clean-Up Day event.
  9. Bring your car to a professional car washing facility since they capture all of the soapy runoff that may otherwise pollute local waters.

Clean Catch Basin - clean environment Dirty Catch Basin - polluted waterways
A clean catch basin means a clean environment. A dirty catch basin means polluted and clogged sewers.

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For clogged catch basins, you can call San Francisco's 3-1-1 or go to sf311.org.

Catch basins are the semi-circular grids that you see at almost every street corner throughout San Francisco. There are close to 23,000 catch basins in the City. They are the main entryway for rainwater and street runoff into our combined sewer system.

Litter in/around catch basins can prevent stormwater from entering the sewer system and  cause property and neighborhood flooding, and can also pollute our waterways. According to the State Water Resource Control Board, urban stormwater runoff is the leading cause of water pollution in California.


Last updated: 6/5/2015 11:15:38 AM